Cryopump

ABSTRACT

A cryopump includes a gas flow regulation member which deflects a flow of gas, which flows in from a shield main opening, from a cryocooler structural portion. The gas flow regulation member is disposed to be adjacent to the cryocooler structural portion such that the gas flow regulation member is in contact with neither a second cooling stage nor a second cryopanel unit of a cryocooler. The gas flow regulation member may be thermally connected to a first cooling stage of the cryocooler.

RELATED APPLICATIONS

Priority is claimed to Japanese Patent Application No. 2015-158508, filed Aug. 10, 2015, the entire content of which is incorporated herein by reference.

BACKGROUND

Technical Field

A certain embodiment of the present invention relates to a cryopump.

Description of Related Art

In general, a cryopump includes two kinds of cryopanel in which temperatures are different from each other. Gas is condensed in a low-temperature cryopanel. A condensation layer grows on the low-temperature cryopanel according to the use of the cryopump. Similarly, a condensation layer grows on a structural portion which supports the low-temperature cryopanel. The grown condensation layers may come into contact with a high-temperature cryopanel. Accordingly, gas is gasified at a contact portion between the high-temperature cryopanel and the condensation layer again and is discharged to the periphery thereof. The gas discharging from the condensation layer may prevent the cryopump sufficiently performing its function. Accordingly, a storage amount of gas at the time of contact may be set to the maximum storage amount of the cryopump.

SUMMARY

According to an aspect of the present invention, there is provided a cryopump including: a cryocooler which includes a first cooling stage which is cooled to a first cooling temperature, a second cooling stage which is cooled to a second cooling temperature which is lower than the first cooling temperature, and a cryocooler structural portion which structurally supports the second cooling stage to the first cooling stage; a radiation shield which includes a shield main opening for receiving a gas, is thermally connected to the first cooling stage, and includes a shield side portion which encloses the second cooling stage and a shield side opening, into which the cryocooler structural portion is inserted, on the shield side portion; a cryopanel unit which is thermally connected to the second cooling stage and is enclosed by the second cooling stage and the shield side portion; and a gas flow regulation member which is disposed to be adjacent to the cryocooler structural portion such that the gas flow regulation member is in contact with neither the second cooling stage nor the cryopanel unit, and deflects the flow of the gas, which flows in from the shield main opening, from the cryocooler structural portion. The cryopanel unit includes a top cryopanel which faces the shield main opening, and the top cryopanel is disposed to form a gap region between the top cryopanel and the cryocooler structural portion. The gas flow regulation member includes an inner edge portion which enters the gap region, and the inner edge portion is covered with the top cryopanel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view schematically showing a cryopump according to an embodiment of the present invention.

FIG. 2 is a top view schematically showing the cryopump shown in FIG. 1.

FIG. 3 is a top view schematically showing the cryopump shown in FIG. 1.

FIG. 4 is a view schematically showing the cryopump shown in FIG. 1 during a vacuum exhaust operation.

FIG. 5 is a side sectional view schematically showing a cryopump according to an embodiment of the present invention.

DETAILED DESCRIPTION

It is desirable to improve a gas storage capacity of a cryopump.

In addition, components or expression of the present invention may be replaced by each other in methods, devices, systems, or the like, and these replacements are also included in aspects of the present invention.

According to the present invention, it is possible to improve a gas storage capacity of a cryopump.

FIG. 1 a side sectional view schematically showing a cryopump 10 according to an embodiment of the present invention. FIGS. 2 and 3 are top views schematically showing the cryopump 10 shown in FIG. 1. FIG. 1 shows a cross section including a center axis A shown by a dashed line. FIGS. 2 and 3 are views when from line B-B. FIG. 3 schematically shows the internal structure of the cryopump 10 shown in FIG. 1. For easy understanding, in FIG. 3, an inlet cryopanel which is disposed in a cryopump intake port is not shown.

For example, the cryopump 10 is attached to a vacuum chamber of an ion implanter, a sputtering apparatus, a vapor deposition apparatus, or other vacuum processing apparatuses, and is used to increase a vacuum degree inside the vacuum chamber to a level required for a vacuum process. The cryopump 10 includes an intake port 12 to receive gas to be exhausted from the vacuum chamber. The gas enters an internal space 14 of the cryopump 10 through the intake port 12.

In addition, hereinafter, terms such as an “axial direction” and a “radial direction” are used to easily indicate positional relationships of components of the cryopump 10. The axial direction indicates a direction (a direction along the center axis A in FIG. 1) passing through the intake port 12, and the radial direction indicates a direction (a direction perpendicular to the center axis A) along the intake port 12. For convenience, a side relatively close to the intake port 12 in the axial direction may be referred to as an “upper side”, and a side relatively far from the intake port 12 may be referred to as a “lower side”. That is, a side relatively far from the bottom portion of the cryopump 10 may be referred to as the “upper side”, and a side relatively close to the bottom portion may be referred to as the “lower side”. A side close to the center (the center axis A in FIG. 1) of the intake port 12 in the radial direction may be referred to as an “inner side”, and a side close to the peripheral edge of the intake port 12 may be referred to as an “outer side”. In addition, the above-described expressions are not related to the disposition of the cryopump 10 when the cryopump 10 is attached to the vacuum chamber. For example, the cryopump 10 may be attached to the vacuum chamber in a state where the intake port 12 is positioned downward in a vertical direction.

In addition, a direction surrounding the axial direction may be referred to a “circumferential direction”. The circumferential direction is a second direction along the intake port 12 and is a tangential direction orthogonal to the radial direction.

The cryopump 10 includes a cryocooler 16, a first cryopanel unit 18, a second cryopanel unit 20, and a cryopump container 70.

For example, the cryocooler 16 is a cryocooler such as a Gifford McMahon type cryocooler (so-called GM cryocooler). The cryocooler 16 is a two-stage cryocooler. Accordingly, the cryocooler 16 includes a first cooling stage 22 and a second cooling stage 24. The cryocooler 16 is configured so as to cool the first cooling stage 22 to a first cooling temperature and cool the second cooling stage 24 to a second cooling temperature. The second cooling temperature is lower than the first cooling temperature. For example, the first cooling stage 22 is cooled to approximately 65K to 120K, preferably, 80K to 100K, and the second cooling stage 24 is cooled to approximately 10K to 20K.

In addition, the cryocooler 16 includes a cryocooler structural portion 21 which structurally supports the second cooling stage 24 to the first cooling stage 22 and structurally supports the first cooling stage 22 to a room-temperature portion 26 of the cryocooler 16. Accordingly, the cryocooler structural portion 21 includes a first cylinder 23 and a second cylinder 25 which coaxially extend in the radial direction. The first cylinder 23 connects the room-temperature portion 26 of the cryocooler 16 to the first cooling stage 22. The second cylinder 25 connects the first cooling stage 22 to the second cooling stage 24. The room-temperature portion 26, the first cylinder 23, the first cooling stage 22, the second cylinder 25, and the second cooling stage 24 are linearly arranged in this order.

A first displacer and a second displacer (not shown) are respectively disposed inside the first cylinder 23 and the second cylinder 25 so as to be reciprocated. A first regenerator and a second regenerator (not shown) are respectively incorporated into the first displacer and the second displacer. Moreover, the room-temperature portion 26 includes a drive mechanism (not shown) for reciprocating the first displacer and the second displacer. The drive mechanism includes a flow path switching mechanism which switches a flow path of a working gas (for example, helium) such that the working gas is repeatedly supplied to or discharged from the inside of the cryocooler 16 periodically.

The cryocooler 16 is connected to a compressor (not shown) of the working gas. The cryocooler 16 expands the working gas compressed by the compressor inside the cryocooler 16 to cool the first cooling stage 22 and the second cooling stage 24. The expanded working gas is recovered to the compressor so as to be compressed again. The cryocooler 16 repeats a thermal cycle which includes supplying and discharging of the working gas and reciprocations of the first displacer and the second displacer synchronized with the supplying and the discharging, and generates chill.

The shown cryopump 10 is a so-called horizontal cryopump. In general, the horizontal cryopump is a cryopump in which the cryocooler 16 is disposed to intersect (generally, to be orthogonal to) the center axis A of the cryopump 10.

The first cryopanel unit 18 includes a radiation shield 30 and an inlet cryopanel 32, and encloses the second cryopanel unit 20. The first cryopanel unit 18 is a cryopanel which is provided to protect the second cryopanel unit 20 from radiation heat from the outside of the cryopump 10 or the cryopump container 70. The first cryopanel unit 18 is thermally connected to the first cooling stage 22. Accordingly, the first cryopanel unit 18 is cooled to the first cooling temperature. The first cryopanel unit 18 has a gap between the first cryopanel unit 18 and the second cryopanel unit 20. Therefore, the first cryopanel unit 18 is not in contact with the second cryopanel unit 20.

The radiation shield 30 is provided to protect the second cryopanel unit 20 from radiant heat of the cryopump container 70. The radiation shield 30 is positioned between the cryopump container 70 and the second cryopanel unit 20, and surrounds the second cryopanel unit 20. The radiation shield 30 includes a shield main opening 34 for receiving a gas from the outside of the cryopump 10 to the internal space 14. The shield main opening 34 is positioned at the intake port 12.

The radiation shield 30 includes a shield front end 36 which defines the shield main opening 34, a shield bottom portion 38 which is positioned on aside opposite to the shield main opening 34, and a shield side portion 40 which connects the shield front end 36 to the shield bottom portion 38. The shield side portion 40 extends from the shield front end 36 to the side opposite to the shield main opening 34 in the axial direction, and extends to surround the second cooling stage 24 in the circumferential direction. The radiation shield 30 has a tubular (for example, cylindrical) shape which has the closed shield bottom portion 38, and is formed in a cup shape. An annular gap 42 is formed between the shield side portion 40 and the second cryopanel unit 20.

In addition, at least a portion of the shield bottom portion 38 may be open. For example, the radiation shield 30 may not be closed by the shield bottom portion 38. That is, both ends of the shield side portion 40 may be open.

The shield side portion 40 includes a shield side opening 44 through which the cryocooler structural portion 21 is inserted. The second cooling stage 24 and the second cylinder 25 are inserted from the outside of the radiation shield 30 into the radiation shield 30 through the shield side opening 44. The shield side opening 44 is an attachment hole which is formed on the shield side portion 40, and, for example, has a circular shape. The first cooling stage 22 is disposed outside the radiation shield 30.

The shield side portion 40 includes an attachment seat 46 of the cryocooler 16. The attachment seat 46 is a flat portion for attaching the first cooling stage 22 to the radiation shield 30, and is slightly recessed when viewed from the outside of the radiation shield 30. The attachment seat 46 forms the outer periphery of the shield side opening 44. The attachment seat 46 is closer to the shield bottom portion 38 than the shield front end 36 in the axial direction. The first cooling stage 22 is attached to the attachment seat 46. Therefore, the radiation shield 30 is thermally connected to the first cooling stage 22.

Instead of the radiation shield 30 being directly attached to the first cooling stage 22, in an embodiment, the radiation shield 30 may be thermally connected to the first cooling stage 22 via an additional heat transfer member. For example, the heat transfer member may be a short hollow tube having flanges on both ends. The heat transfer member may be fixed to the attachment seat 46 by one end flange, and may be fixed to the first cooling stage 22 by the other end flange. The heat transfer member may surround the cryocooler structural portion 21 and may extend from the first cooling stage 22 to the radiation shield 30. The shield side portion 40 may include the heat transfer member.

In the embodiment shown in the drawings, the radiation shield 30 is configured of an integral tubular shape. Instead of this, the radiation shield 30 may be configured of the entire tubular shape including multiple parts. The multiple parts may be disposed to have gaps to each other. For example, the radiation shield 30 may be divided into two portions in the axial direction. In this case, the upper portion of the radiation shield 30 is a tube having both open ends, and includes the shield front end 36 and a first portion of the shield side portion 40. The lower portion of the radiation shield 30 has an open upper end and a close lower end, and includes a second portion of the shield side portion 40 and the shield bottom portion 38. As described above, the lower portion of the radiation shield 30 may be a tube which does not have the shield bottom portion 38 and have both open ends. A slit is formed, which extends in the circumferential direction between the first portion and the second portion of the shield side portion 40. The slit may be at least a portion of the shield side portion 40. Alternatively, the upper half of the shield side opening 44 may be formed on the first portion of the shield side portion 40, and the lower half thereof may be formed on the second portion of the shield side portion 40.

The inlet cryopanel 32 is provided on the shield main opening 34 to protect the second cryopanel unit 20 from radiant heat from a heat source outside the cryopump 10. For example, the heat source outside the cryopump 10 is a heat source inside a vacuum chamber to which the cryopump 10 is attached. The inlet cryopanel 32 can limit not only entering of the radiant heat but also entering of gas molecules. The inlet cryopanel 32 occupies a portion of an opening area of the shield main opening 34 so as to limit gas flowing in the internal space 14 through the shield main opening 34 to a predetermined amount. An annular opening area 48 is formed between the inlet cryopanel 32 and the shield front end 36.

The inlet cryopanel 32 includes a louver portion 50, and multiple louver attachment portions 52 for attaching the louver portion 50 to the shield front end 36. The inlet cryopanel 32 is thermally connected to the first cooling stage 22 via the louver attachment portion 52 and the radiation shield 30.

The louver portion 50 has multiple louvers which are linearly extends in a first direction in the shield main opening 34. The multiple louvers are arranged in a second direction perpendicular to the first direction in the shield main opening 34. The multiple louvers are arranged to be parallel to each other, and each louver is disposed to be inclined to an opening surface. As shown in the drawings, the louvers on one side and the louvers on the other side with respect to the center axis A are inclined in directions opposite to each other. The multiple louvers are densely arranged in the second direction to cover (that is, such that the second cryopanel unit 20 is not viewed from the outside of the cryopump 10) the second cryopanel unit 20 which is positioned immediately below the multiple louvers. The multiple louvers have lengths different from each other in the first direction such that the entire shape formed by the arrangement is a circular shape.

Accordingly, gas which is to be exhausted by the cryopump 10 enters the internal space 14 through gaps between louvers of the louver portion 50 or the opening region 48 from the outside of the cryopump 10.

The inlet cryopanel 32 may have other shapes. For example, the louver portion 50 may have multiple annular louvers which are coaxially disposed. Alternatively, the inlet cryopanel 32 may be one plate-shaped member.

The second cryopanel unit 20 is attached to the second cooling stage 24 to surround the second cooling stage 24. Accordingly, the second cryopanel unit 20 is thermally connected to the second cooling stage 24, and the second cryopanel unit 20 is cooled to the second cooling temperature. The second cryopanel unit 20 and the second cooling stage 24 are enclosed by the shield side portion 40.

The second cryopanel unit 20 includes a top cryopanel 60 which faces the shield main opening 34, and one or multiple second cryopanel 62. Since the annular gap 42 is formed between the top cryopanel 60 and the second cryopanel 62, and the shield side portion 40, both the top cryopanel 60 and the second cryopanel 62 are not in contact with the radiation shield 30.

The top cryopanel 60 is a portion of the second cryopanel unit 20 which is closest to the inlet cryopanel 32. The top cryopanel 60 is disposed between the shield main opening 34 or the inlet cryopanel 32 and the cryocooler 16 in the axial direction. The top cryopanel 60 is positioned at the center portion of the internal space 14 of the cryopump 10 in the axial direction. Accordingly, a main accommodation space 65 of a condensation layer is widely formed between the front surface of the top cryopanel 60 and the inlet cryopanel 32. The main accommodation space 65 of a condensation layer occupies the upper half the internal space 14.

The top cryopanel 60 is an approximately flat-plated cryopanel which is disposed to be perpendicular to the axial direction. That is, the top cryopanel 60 extends in the radial direction and circumferential direction. As shown in FIGS. 2 and, 3, the top cryopanel 60 is a disk-shaped panel which has approximately the same size (for example, a projected area) as that of the louver portion 50. In addition, in FIG. 3, the radial direction and the circumferential direction are respectively indicated by arrow C and arrow D.

The top cryopanel 60 is disposed to form a gap region 66 between the cryocooler structural portion 21 and the top cryopanel 60. The gap region 66 is a space which is formed between the rear surface of the top cryopanel 60 and the second cylinder 25 in the axial direction.

Multiple second cryopanels 62 are arranged between the top cryopanel 60 and the shield bottom portion 38. Each of the second cryopanels 62 is an approximately flat-plated cryopanel which is disposed to be perpendicular to the axial direction. The second cryopanels 62 are covered by the top cryopanel 60. The top cryopanel 60 may be only one of the multiple second cryopanels 62.

Each of the second cryopanels 62 may have the same shape as that of the top cryopanel 60, or may have a shape different from that of top cryopanel 60. As shown in FIG. 1, each of the second cryopanels 62 is disposed on one side of the center axis A, extends toward the shield side portion 40, and may have a semicircular shape. In addition, the second cryopanel 62 may have other shapes. For example, similarly to a typical cryopump, the second cryopanel 62 may have a shape having a truncated conical side surface. The second cryopanel 62 may extend toward the shield side portion 40 from both sides of the second cooling stage 24.

An adsorption material such as activated carbon is provided on the second cryopanel 62. For example, the adsorption material is bonded to the rear surface of the second cryopanel 62. Accordingly, the front surface of the second cryopanel 62 function as a condensation surface, and the rear surface thereof functions as an adsorption surface. The adsorption material may be provided on the front surface of the second cryopanel 62. Similarly, the top cryopanel 60 may have an adsorption material on the front surface and/or the rear surface. Alternatively, the top cryopanel 60 may not have an adsorption material.

A cryopanel attachment member 64 is provided on the second cryopanel unit 20. The cryopanel attachment member 64 has an elongated shape which extends in the axial direction, and the top cryopanel 60 and the second cryopanels 62 are fixed to the outer surface of the cryopanel attachment member 64. In addition, the second cooling stage 24 is fixed to the inner surface of the cryopanel attachment member 64. The cryopanel attachment member 64 is attached to the center portion of the top cryopanel 60. Accordingly, the top cryopanel 60 and the second cryopanels 62 are thermally connected to the second cooling stage 24 via the cryopanel attachment member 64. In addition, the top cryopanel 60 and the second cryopanels 62 may be directly connected to the second cooling stage 24 without using the cryopanel attachment member 64.

The cryopump container 70 is a case of the cryopump 10 which accommodates the first cryopanel unit 18, the second cryopanel unit 20, and the cryocooler 16, and is a vacuum vessel which is configured to hold vacuum airtightness of the internal space 14. The cryopump container 70 includes the first cryopanel unit 18 and the cryocooler structural portion 21 in a non-contact state. The cryopump container 70 is attached to the room-temperature portion 26 of the cryocooler 16.

The intake port 12 is defined by the front end of the cryopump container 70. The cryopump container 70 includes an intake port flange 72 which extends toward the outside in the radial direction from the front end. The intake port flange 72 is provided on the entire periphery of the cryopump container 70. The cryopump 10 is attached to a vacuum chamber of an object to be vacuum-exhausted using the intake port flange 72.

The cryopump 10 includes a gas flow regulation member 80 which is configured to deflect a flow of gas which flows in from the shield main opening 34 from the cryocooler structural portion 21. The gas flow regulation member 80 is configured to deflect the flow of gas, which flows into the main accommodation space 65 through the louver portion 50 or the opening region 48, from the second cylinder 25. The gas flow regulation member 80 may be a gas flow deflection member or a gas flow reflection member which is disposed to be adjacent to the cryocooler structural portion 21 or the second cylinder 25 above the cryocooler structural portion 21 or the second cylinder 25.

The gas flow regulation member 80 is disposed to be adjacent to the cryocooler structural portion 21 to be in contact with neither the second cooling stage 24 nor the second cryopanel unit 20. The gas flow regulation member 80 is disposed to be adjacent to the second cylinder 25 to be not in contact with any of the second cooling stage 24, the second cryopanel unit 20, and the second cylinder 25. Accordingly, the gas flow regulation member 80 is thermally and structurally separated from a portion which is cooled to the second cooling temperature and structural portions which support the portion.

The gas flow regulation member 80 includes an outer edge portion 82 and an inner edge portion 84. The outer edge portion 82 and the inner edge portion 84 form one flat plate. Accordingly, the outer edge portion 82 is a radially outside portion of the flat plate, and the inner edge portion 84 is a radially inside portion of the flat plate. A clearance 86 is provided between the flat plate and the second cylinder 25, and the flat plate is disposed along the second cylinder 25. The flat plate is separated from the second cylinder 25 by the clearance 86 in the axial direction. Accordingly, the flat plate is not in contact with any of the second cylinder 25, the top cryopanel 60, the cryopanel attachment member 64, and the second cooling stage 24.

Moreover, in an embodiment, instead of the flat plate, the gas flow regulation member 80 may include a curved plate, a bent plate, or a tubular plate which has a clearance between the gas flow regulation member 80 and the second cylinder 25 in the axial direction and extends along the second cylinder 25 in the radial direction. The curved plate may have a curved shape along the surface of the second cylinder 25. The curved plate may have an arch shape which covers the upper portion of the second cylinder 25. The bent plate may have a bent shape along the surface of the second cylinder 25. The tubular plate may be extended to be coaxial with the second cylinder 25 to surround the second cylinder 25.

The gas flow regulation member 80 extends from the shield side portion 40 toward the gap region 66. The outer edge portion 82 is mounted on the shield side portion 40 between the shield front end 36 and the shield side opening 44. The outer edge portion 82 is disposed between the top cryopanel 60 and the shield side opening 44 (or second cylinder 25) in the axial direction.

The outer edge portion 82 is fixed to the shield side portion 40 (for example, attachment seat 46) using an appropriate fastening member (not shown) such as a bolt. The fastening member may be attached to the upper side or the lower side of the outer edge portion 82. The fastening member may have a protrusion (for example, a head portion) which protrudes toward the inside in the radial direction from the shield side portion 40. The fastening member may fix both the gas flow regulation member 80 and the first cooling stage 22 to the shield side portion 40.

In this way, the gas flow regulation member 80 is thermally connected to the first cooling stage 22. The outer edge portion 82 is mounted on the shield side portion 40. Therefore, the gas flow regulation member 80 is thermally connected to the first cooling stage 22 via the radiation shield 30. Accordingly, the gas flow regulation member 80 is cooled to the first cooling temperature. Moreover, the outer edge portion 82 may be directly attached to the first cooling stage 22. In this case, the gas flow regulation member 80 may extend toward the gap region 66 through the gap between the above-described heat transfer member and the second cylinder 25 and the shield side opening 44 from the first cooling stage 22.

The outer edge portion 82 faces the shield main opening 34. Since the outer edge portion 82 is positioned outside the louver portion 50 in the radial direction, the outer edge portion 82 is exposed. As shown in FIGS. 2 and 3, the outer edge portion 82 can be viewed through the opening region 48 and the annular gap 42 from the outside of the cryopump 10. The gas flow regulation member 80 has an outside region which does not overlap the top cryopanel 60 when viewed in the axial direction.

Meanwhile, the inner edge portion 84 enters the gap region 66. The inner edge portion 84 is disposed between the outer peripheral end of the top cryopanel 60 and the center axis A in the radial direction. Accordingly, the inner edge portion 84 is covered with the top cryopanel 60. However, the inner edge portion 84 is separated from the second cooling stage 24 in the radial direction by the gap region 66, and the inner edge portion 84 is not in contact with the second cooling stage 24.

In FIG. 3, a portion (including the inner edge portion 84) of the gas flow regulation member 80 which is covered with the top cryopanel 60 is indicated by a broken line. The inner edge portion 84 cannot be viewed from the outside of the cryopump 10. In other words, the gas flow regulation member 80 includes an inside region which overlaps with the top cryopanel 60 when viewed in the axial direction.

In this way, the gas flow regulation member 80 is inserted into the gap region 66 between the top cryopanel 60 and the second cylinder 25, and thus, the inlet of the gap region 66 is narrowed. Accordingly, it is possible to decrease gas which flows from the main accommodation space 65 into the gap region 66.

The gas flow regulation member 80 is extended in the circumferential direction along the shield side portion 40 so as to at least partially close the annular gap 42. The gas flow regulation member 80 is locally provided at the same position as that of the shield side opening 44 in the circumferential direction. The gas flow regulation member 80 is formed in a rectangular shape when viewed from the above. In addition, the gas flow regulation member 80 may be provided to be longer in the circumferential direction, and for example, may be provided along the shield side portion 40 over the entire circumference.

As described with reference to FIGS. 1 to 3, the gas flow regulation member 80 extends from the portion immediately above the base portion (that is, high-temperature end) of the second cylinder 25 toward the tip portion (that is, low-temperature end) of the second cylinder 25 in the radial direction. The gas flow regulation member 80 covers at least the base portion of the second cylinder 25.

Hereinafter, an operation of the cryopump 10 having the above-described configuration will be described. When the cryopump 10 is operated, first, the pressure inside the vacuum chamber is roughly set to approximately 1 Pa by other appropriate roughing pumps before the cryopump 10 is operated. Thereafter, the cryopump 10 is operated. The first cooling stage 22 and the second cooling stage 24 are respectively cooled to the first cooling temperature and the second cooling temperature by driving of the cryocooler 16. Accordingly, the first cryopanel unit 18 and the second cryopanel unit 20, which are thermally connected to the first cooling stage 22 and the second cooling stage 24, are cooled to the first cooling temperature and the second cooling temperature. Since the gas flow regulation member 80 is thermally connected to the first cooling stage 22, the gas flow regulation member 80 is cooled to the first cooling temperature.

The inlet cryopanel 32 cools gas flying from the vacuum chamber toward cryopump 10. Gas is condensed so as to have a sufficiently low vapor pressure (for example, 10⁻⁸ Pa or less) at the first cooling temperature on the surface of the inlet cryopanel 32. This gas may be referred to as a first kind of gas. For example, the first kind of gas is water vapor. In this way, the inlet cryopanel 32 through which the first kind of gas can be exhausted. A portion of gas having a vapor pressure which is not sufficiently low at the first cooling temperature can enter the main accommodation space 65 through the louver portion 50 or the opening region 48. Alternatively, the other portion of the gas is reflected by the inlet cryopanel 32, and does not enter the main accommodation space 65.

The gas entering the main accommodation space 65 is cooled by the second cryopanel unit 20. Gas having a sufficiently low vapor pressure (for example, 10⁻⁸ Pa or less) at the second cooling temperature is condensed on the surface of the second cryopanel unit 20. This gas may be referred to as a second kind of gas. For example, the second kind of gas is argon. In this way, the second cryopanel unit 20 can exhaust the second kind of gas. Since the second cryopanel unit 20 directly faces the main accommodation space 65, as shown in FIG. 4, a condensation layer 88 of the second kind of gas largely grows on the front surface of the top cryopanel 60. In addition, the second kind of gas is gas which is not condensed at the first cooling temperature.

Gas having a vapor pressure which is not sufficiently low at the second cooling temperature is adsorbed to the adsorption material of the second cryopanel unit 20. This gas may be referred to as a third kind of gas. For example, the third kind of gas is hydrogen. In this way, the second cryopanel unit 20 can exhaust the third kind of gas. Accordingly, the cryopump 10 exhausts various gas by condensation and adsorption, and a vacuum degree of the vacuum chamber can reach a desired level.

Since the gas flow regulation member 80 covers the second cylinder 25, the second cylinder 25 is not exposed to the shield main opening 34. The gas flow regulation member 80 can deflect the flow of the second kind of gas, which is directed to the second cylinder 25 from the main accommodation space 65, in other directions. Accordingly, the second cylinder 25 has a temperature distribution from the first cooling temperature to the second cooling temperature on the surface of the second cylinder 25. However, the second kind of gas, which is condensed at the surface portion of the second cooling temperature or a temperature in the vicinity of the second cooling temperature, is little present, or is not present. In addition, since the gas flow regulation member 80 has the first cooling temperature, the second kind of gas is not condensed on the surface of the gas flow regulation member 80.

A portion of the gas entering the main accommodation space 65 may be reflected by the gas flow regulation member 80. At least a portion of the reflected gas is directed to the second cryopanel unit 20. Alternatively, a portion of the reflected gas is directed to the radiation shield 30 or the inlet cryopanel 32, is reflected at the radiation shield 30 or the inlet cryopanel 32 again, and is directed to the second cryopanel unit 20. In this way, the second cryopanel unit 20 can exhaust the second kind of gas by condensation, and can exhaust the third kind of gas by adsorption.

An exemplified cryopump does not have the gas flow regulation member 80 and has a cryocooler cover which is cooled to the second cooing temperature. For example, the cryopump is disclosed in Japanese Unexamined Patent Application Publication No. 2009-275672 and Japanese Unexamined Patent Application Publication No. 2015-1186, each of which is incorporated herein by reference. The cryocooler cover extends from the second cooling stage of the cryocooler toward the radiation shield. Accordingly, the distal end of the cryocooler cover is very close to the radiation shield. The second kind of gas is condensed on the cryocooler cover. Accordingly, before the maximum condensation layer of the second kind of gas on design grows on the top cryopanel 1, the condensate on the cryocooler cover may come into contact with the radiation shield. The condensate on the cryocooler cover is re-vaporized, and thus, the cryopump may not provide the maximum storage amount on design.

According to cryopump 10 of the present embodiment, the gas flow regulation member 80 can reduce or prevent the growth of the condensation layer at the location that the portion having the first cooling temperature and the portion having second cooling temperature approach. Therefore, the cryopump 10 can prevent the contact between the condensation layer and the portion having first cooling temperature, and can reduce or prevent re-vaporization of the condensation layer. As a result, it is possible to condense a large amount of the second kind of gas on the front surface of the top cryopanel 60 in the main accommodation space 65. Therefore, it is possible to improve the gas storage capacity of the cryopump 10.

As shown in FIG. 5, in an embodiment, the cryopump 10 may comprise a cryocooler cover 90 in addition to the gas flow regulation member 80. The cryocooler cover 90 forms part of the cryocooler structural portion 21. The cryocooler cover 90 is a cylindrical member surrounding the second cylinder 25 and extends from the second cooling stage 24 of the cryocooler 16 toward the radiation shield 30. An end of the cryocooler cover 90 is fixed to the second cylinder 25 and thus the cryocooler cover 90 is cooled to the second cooling temperature. The distal end of the cryocooler cover 90 is located close to the outer edge portion 82 of the cryocooler cover 90 and the radiation shield 30; however, the cryocooler cover 90 is not in contact with them.

The second cryopanel unit 20 includes the top cryopanel 60 which faces the shield main opening 34, and the top cryopanel 60 is disposed to form the gap region 66 between the top cryopanel 60 and the cryocooler cover 90. The gas flow regulation member 80 extends from the shield side portion 40 toward the gap region 66. Alternatively, the gas flow regulation member 80 may extend from the first cooling stage 22. The gas flow regulation member 80 is separated from the cryocooler cover 90 by the clearance 86 in the axial direction of the cryopump 10. The gas flow regulation member 80 includes the inner edge portion 84 which enters the gap region 66, and the inner edge portion 84 is covered with the top cryopanel 60. In other words, the cryocooler cover 90 is covered with the top cryopanel 60 and the gas flow regulation member 80 in combination, and thus, the cryocooler cover 90 is not exposed to the shield main opening 34.

In this case, the gas flow regulation member 80 can reduce or prevent the growth of the condensation layer on the cryocooler cover 90. Therefore, the cryopump 10 can prevent the contact between the condensation layer and the portion having first cooling temperature, and can reduce or prevent re-vaporization of the condensation layer. As a result, it is possible to condense a large amount of the second kind of gas on the front surface of the top cryopanel 60 in the main accommodation space 65. Therefore, it is possible to improve the gas storage capacity of the cryopump 10.

In particular, the gas flow regulation member 80 enters the gap region 66 between the top cryopanel 60 and the cryocooler cover 90, and thus, the inlet of the gap region 66 is narrowed. Accordingly, it is possible to decrease gas which flows from the main accommodation space 65 into the gap region 66.

It should be understood that the invention is not limited to the above-described embodiment, but may be modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention.

In an embodiment, the gas flow regulation member 80 may be thermally connected to the portion having the first cooling temperature or the portion having a temperature in the vicinity of the first cooling temperature in the cryocooler structural portion 21. According to this, the gas flow regulation member 80 may be in contact with the cryocooler structural portion 21. In this way, since the gas flow regulation member 80 can be maintained to the temperature which is sufficiently higher than the second cooling temperature, the second kind of gas which is condensed on the surface of the gas flow regulation member 80 is little present or is not present.

In an embodiment, the gas flow regulation member 80 may not enter the gap region 66. The gas flow regulation member 80 may be disposed between the outer peripheral end of the top cryopanel 60 and the shield side portion 40 in the radial direction. The gas flow regulation member 80 may not overlap the top cryopanel 60 when viewed in the axial direction, and the entire gas flow regulation member 80 may be viewed from the outside of the cryopump 10 through the opening region 48 and the annular gap 42. In this way, it is possible to approximately reduce or prevent the growth of the condensation layer at the location that the portion having the first cooling temperature and the portion having the second cooling temperature approach. 

What is claimed is:
 1. A cryopump comprising: a cryocooler which includes a first cooling stage which is cooled to a first cooling temperature, a second cooling stage which is cooled to a second cooling temperature which is lower than the first cooling temperature, and a cryocooler structural portion which structurally supports the second cooling stage to the first cooling stage; a radiation shield which includes a shield main opening for receiving a gas, is thermally connected to the first cooling stage, and includes a shield side portion which encloses the second cooling stage, wherein a shield side opening into which the cryocooler structural portion is inserted is on the shield side portion; a cryopanel unit which is thermally connected to the second cooling stage, wherein the cryopanel and the second cooling stage are enclosed by the shield side portion; and a gas flow regulation member which is in contact with neither the second cooling stage nor the cryopanel unit, and is disposed to be adjacent to the cryocooler structural portion such that the gas flow regulation member deflects the flow of the gas which flows in from the shield main opening, from the cryocooler structural portion, wherein the cryopanel unit includes a top cryopanel which faces the shield main opening, and the top cryopanel is disposed to forma gap region between the top cryopanel and the cryocooler structural portion, and wherein the gas flow regulation member includes an inner edge portion which enters the gap region, and the inner edge portion is covered with the top cryopanel.
 2. The cryopump according to claim 1, wherein the gas flow regulation member is thermally connected to the first cooling stage.
 3. The cryopump according to claim 1, wherein the gas includes a second kind of gas which is not condensed at the first cooling temperature and is condensed at the second cooling temperature, and wherein the gas flow regulation member is configured to reflect the second kind of gas.
 4. The cryopump according to claim 1, wherein the gas flow regulation member extends from the shield side portion or the first cooling stage toward the gap region.
 5. The cryopump according to claim 1, wherein the radiation shield includes a shield front end which defines the shield main opening, and the shield side portion extends from the shield front end toward a side opposite to the shield main opening, and wherein the gas flow regulation member includes an outer edge portion which faces the shield main opening, and the outer edge portion is mounted on the shield side portion between the shield front end and the shield side opening.
 6. The cryopump according to claim 1, wherein the cryocooler structural portion includes a cryocooler cylinder which connects the second cooling stage to the first cooling stage, and wherein the gas flow regulation member includes a flat plate, a curved plate, a bent plate, or a tubular plate which is disposed along the cryocooler cylinder in a state where a clearance is provided between the cryocooler cylinder and the plate. 